By using heteropoly acid/acetone system as chemical extractant

a novel process was developed to selectively remove nitrogen-containing compounds from lubricating oil base stocks. The results showed that the process could effectively reduce the content of nitrogen-containing compounds and thus greatly increase the anti-oxidative stability of the lubricating oil base stocks

without significantly lowering sulfur content and affecting other physical and chemical properties of the refined base stocks. This work may provide an alternative way for denitrification of lubricating oil base stocks.